1. 程式人生 > 其它 >poj 1094(拓撲排序,三種情況:1正好排好,2正好有環,3到最後也沒排好,也沒有環,多重解)

poj 1094(拓撲排序,三種情況:1正好排好,2正好有環,3到最後也沒排好,也沒有環,多重解)

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int n,flag,edge[30][30],indegree[30],indgr_tmp[30],ans[30];
void topo(){
    int i,j,s,pos;
    for(i=0;i<n;i++){
        indgr_tmp[i] = indegree[i];
    }
    pos = 0;
    for(i=0;i<n;i++){
        s = 0;
        
for(j=0;j<n;j++){ if(indgr_tmp[j]==0){ s++; pos = j; } } if(s==0){ flag = 1;// return; } if(s>1){ flag = -1;//有多重解 } ans[i] = pos; indgr_tmp[pos]=-1;
for(j=0;j<n;j++){ if(edge[pos][j]){ indgr_tmp[j]--; } } } } int main(){ int m,i,j,sign; char a[1000][3]; while(scanf("%d%d",&n,&m)==2&&n){ sign = 0; memset(indegree,0,sizeof indegree); memset(edge,0,sizeof
edge); for(i=0;i<m;i++){ scanf("%s",a[i]); if(sign==1)continue; flag = 0; edge[a[i][0]-'A'][a[i][2]-'A'] = 1; indegree[a[i][2]-'A']++; memset(ans,0,sizeof ans); memset(indgr_tmp,0,sizeof indgr_tmp); topo(); if(flag==1){ printf("Inconsistency found after %d relations.\n",i+1); sign = 1; } if(flag==0){ printf("Sorted sequence determined after %d relations: ",i+1); for(j=0;j<n;j++){ printf("%c",ans[j]+'A'); } printf(".\n"); sign = 1; } } if(flag==-1){ printf("Sorted sequence cannot be determined.\n"); } } return 0; }